noinline / notail as part of a function prototype

[daurnimator]

I just recalled something from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66826

Now dlsym (and other dl-functions) secretly take shadow parameter - return address on stack

I wonder if we need to reflect this somehow?

Originally posted by @daurnimator in #2598

llvm has a notail annotation for function calls. this could be a possible use case for a @call() builtin. we could have an enum for Inline, NoInline, MustTail, and NoTail, and unify the builtin with @newStackCall.

Originally posted by @emekoi in #2598

I also would like to allow noinline (with the implication of notail) as part of a function prototype. This way functions such as dlsym can properly document how to call them, instead of being footguns at the callsites.

With this implemented, solving this problem would be as simple as adding "noinline" to the extern fn prototype.

Originally posted by @andrewrk in #2598

[andrewrk]

Thanks for filing the issue 👍